More women with early-stage breast cancer may be able to avoid chemotherapy

Results from a large clinical trial called TAILORx showed that more women with early-stage breast cancer may now be able to avoid chemotherapy after surgery. The women who participated in the study had hormone receptor-positive, HER2-negative, axillary node-negative breast cancer, which is the most common type of breast cancer.

Breast cancers that have estrogen receptors and/or progesterone receptors but do not have HER2 are known as hormone receptor-positive, HER2-negative. Estrogen and progesterone receptors are proteins found in and on cells. Cancers with these receptors may depend on the hormones estrogen and/or progesterone to grow. HER2 is another type of specialized protein on the surface of breast cells that also affects tumor growth. Axillary node-negative breast cancer means that the lymph nodes in the armpit area do not contain cancer.

This type of breast cancer is typically treated with hormone therapy. Women who have a high risk of a breast cancer recurrence also receive chemotherapy, called adjuvant chemotherapy. A recurrence is when cancer comes back after treatment. A test called the 21-gene expression assay (Oncotype DX Breast Recurrence Score) is used to find out a woman’s risk of having a recurrence. The test is done using a sample of the tumor taken during a biopsy. A higher score means a higher risk of recurrence. Usually, women with a Breast Recurrence Score up to 10 receive only hormone therapy. Women with a score of 26 to 100 receive both hormone therapy and chemotherapy. But there is currently no standard of care for a mid-range score of 11 to 25. It is estimated that about 40% of women with a mid-range score currently receive chemotherapy. Side effects from chemotherapy may include nausea, vomiting, pain, and hair loss, and such long-term problems as infertility and neuropathy.

Of the 10,273 women who participated in this clinical trial, 6,711 had a mid-range score and were randomly placed into 2 groups. The first group received hormone therapy alone, while the second group received hormone therapy plus chemotherapy. Overall, hormone therapy alone was as effective as hormone therapy plus chemotherapy for many women. Results did show that adding chemotherapy to hormone therapy was beneficial for women 50 years or younger with a Breast Recurrence Score of 16 to 25. After 9 years, researchers found that:

About 83% of women receiving only hormone therapy were cancer-free compared with about 84% of those receiving hormone therapy plus chemotherapy.

Around 95% of women in both groups had not had a distant recurrence.

Overall survival was about 94% for both groups.

The study results suggest that women older than 50 with a Breast Recurrence Score up to 25 and women age 50 and younger with a score of 15 or below may be able to avoid chemotherapy.